Metabolism of prostaglandin F2 alpha in sheep.

The metabolism of prostaglandin F2 alpha (PGF2 alpha) in ewes was studied after im injection of 9 beta-3H-labeled PGF2 alpha. About 75% of injected radioactivity was excreted in urine within 6 hr, whereas less than 1% was excreted in the milk over 3 days. Most identified urinary metabolites were formed through well known reactions involving oxidation of the hydroxyl group at carbon 15, saturation of double bonds, and oxidation of both carbon chains. However, some metabolites underwent more extensive oxidation of the carbon chain than had been seen before in other species. This might have taken place through catabolic activity of the gastrointestinal microflora followed by reabsorption into the circulation.